High-end Climate Change Research Articles

Application of the Global Uncertainty and Sensitivity Analysis to assess the importance of deadwood characteristics for forest biodiversity

AbstractData acquisition for sustainable forest management has focused on obtaining high quality information to estimate biomass. Improving the quality of non-timber sustainability indicators, like deadwood volume, has been a minor interest. To explore how inventory approaches could be improved, we applied a Global Uncertainty and Sensitivity Analysis (GUSA) to evaluate which factors propagate more errors in deadwood modelling and how better data collection can minimize them. The impact of uncertainty on deadwood characteristics (diameter, collapse ratio, decay class, tree species, and position) was explored under stakeholders´ preferences, management actions, and climate change scenarios. GUSA showed that removing the prediction error in deadwood tree species and diameter would alter the most the total uncertainty in deadwood volume. We found that assessment of high deadwood volume was less uncertain for the scenarios where small deadwood items were left decaying on the forest floor (BAU) and for high-end climate change scenario (RCP8.5) which resulted in lower deadwood accumulation in forest stands and therefore also in lower likelihood of erroneous estimates. Reduced uncertainty in tree species and diameter class will elevate the certainty of deadwood volume to a similar level achieved in living biomass estimation. Our uncertainty and sensitivity analysis was successful in ranking factors propagating errors in estimate of deadwood and identified a strategy to minimize uncertainty in predicting deadwood characteristics. The estimation of uncertainty in deadwood levels under the scenarios developed in our study can help decision makers to evaluate risk of decreasing deadwood value for biodiversity conservation and climate change mitigation.

The projected futures of water resources vulnerability under climate and socioeconomic change in the Yangtze River Basin, China

Despite being one of the most abundant water resources globally, the Yangtze River Basin (YRB) region is facing substantial risks aggravated by climatic and anthropogenic changes. Here, we adopted an integrated framework to investigate the plausible futures of water resource provisioning in YRB under current and future conditions on the sub-watershed level: (i) a process-based model (InVEST) was used to project the water yield of the whole of YRB in the nearest future (2040–2060) and distant future (2080–2100) and (ii) a socio-ecological index was developed to assess the spatio-temporal patterns of water resources vulnerability (WRV). Model projections indicated that several water-rich areas in the southeastern YRB would suffer declining water yield in the future. While water yield was projected to increase in some drier regions in the northwest. Future changes in the basin-level vulnerability were projected to decrease under low emissions scenarios (RCP2.6) combined with a sustainability socioeconomic scenario (SSP1). The greatest increase in vulnerability was projected under the medium-to-high end (RCP7.0) rather than high-end (RCP8.5) climate change scenario. The areas with high WRV were distributed in sub-watersheds near Taihu Lake and the source of the Yangtze River. Climate and socioeconomic change were projected to have different roles in shaping the future dynamics of WRV, with precipitation reduction and water consumption increase being likely to result in increased WRV levels in the southeastern lower reaches and the middle reaches, respectively. Our study added new spatial data on projected water resource dynamics for the region of vital ecological and economic importance in Asia. The areas prone to increased WRV should be prioritised in future water resources management practices. The assessment approach used in this study integrated concurrent measures from both subjective and objective perspectives and could be used in relevant studies on exploring how future vulnerability could respond to environmental changes.

Potential for land and water management adaptations in Mediterranean croplands under climate change

CONTEXTThe Mediterranean Basin has been identified as a climate change “hotspot”, a region where increased warming and drying are expected to occur at rates faster than the global average. Increasing scientific attention has therefore been drawn to the repercussions of climate change for the Mediterranean's diverse and valued agricultural sector. The extent to which these repercussions vary throughout the region, owing both to a non-uniform distribution of climatic hazards and to uneven adaptive capacities of farmers, remains however unquantified. OBJECTIVEWe hereby provide a comprehensive spatial assessment of the potential to implement different farm-based land and water management adaptations across the Mediterranean's croplands, and evaluate the extent to which different regions see a match or a mismatch between areas of adaptation need and areas of adaptation capacity. METHODSThis approach made use of spatial multi-criteria analysis to evaluate the suitability of different farm adaptations, and relied on the Ecocrop climate suitability model and climate data on changing duration or frequency of extremes to identify areas of adaptation need under a high-end climate change scenario. The adaptations explored in this work span a range of sustainable approaches addressing different components of the farming system (soil-based, water-based, and crop-based adaptations). For each sub-system, we compared the potential to implement an adaptation representing an incremental change vs. one involving greater transformation. RESULTS AND CONCLUSIONSResults indicate a worsening of climatic conditions for all croplands in the region, and particularly within the Mediterranean extents of Egypt, Turkey, Greece, Spain, Morocco, Bosnia and Herzegovina, and Israel. In more than half of these countries, >60% of highly affected Mediterranean areas, on average, see no tangible potential to implement adaptations. Importantly, potentials for adaptation, and particularly of transformational adaptations having the greatest hypothesized capacity to buffer against the effects of climate change, are found to be lower within areas where the most adverse climate change hazards are forecast to occur. SIGNIFICANCEFor regions found to be approaching so-called limits to adaptation, this research contributes to growing calls for consideration of more transformational options, alongside the opportunities and sacrifices these options entail. For regions where considerable (yet unrealized) adaptation capacity is found to match areas of adaptation need, this paper instead presents a basis for further investigation on how to bridge adaptation capacity and preparedness.

Future climate change impact on wildfire danger over the Mediterranean: the case of Greece

Recent studies have shown that temperature and precipitation in the Mediterranean are expected to change, contributing to longer and more intense summer droughts that even extend out of season. In connection to this, the frequency of forest fire occurrence and intensity will likely increase. In the present study, the changes in future fire danger conditions are assessed for the different regions of Greece using the Canadian fire weather index (FWI). Gridded future climate output as estimated from three regional climate models from the Coordinated Regional Downscaling Experiment are utilized. We use three representative concentration pathways (RCPs) consisting of an optimistic emissions scenario where emissions peak and decline beyond 2020 (RCP2.6), a middle-of-the-road scenario (RCP4.5) and a pessimistic scenario, in terms of mitigation where emissions continue to rise throughout the century (RCP8.5). Based on established critical fire FWI threshold values for Greece, the future change in days with critical fire danger were calculated for different areas of Greece domains. The results show that fire danger is expected to progressively increase in the future especially in the high-end climate change scenario with southern and eastern regions of Greece expected to have up to 40 additional days of high fire danger relative to the late 20th century, on average. Crete, the Aegean Islands, the Attica region, as well as parts of Peloponnese are predicted to experience a stronger increase in fire danger.

Large variability in response to projected climate and land-use changes among European bumblebee species.

Bumblebees (Bombus ssp.) are among the most important wild pollinators, but many species have suffered from range declines. Land-use change, agricultural intensification, and the associated loss of habitat have been identified as drivers of the observed dynamics, amplifying pressures from a changing climate. However, these drivers are still underrepresented in continental-scale species distribution modeling. Here, we project the potential distribution of 47 European bumblebee species in 2050 and 2080 from existing European-scale distribution maps, based on a set of climate and land-use futures simulated through a regional integrated assessment model and consistent with the RCP-SSP scenario framework. We compare projections including (1) dynamic climate and constant land use (CLIM); (2) constant climate and dynamic land use (LU); and (3) dynamic climate and dynamic land use (COMB) to disentangle the effects of land use and climate change on future habitat suitability, providing the first rigorous continental-scale assessment of linked climate-land-use futures for bumblebees. We find that direct climate impacts, although variable across species, dominate responses for most species, especially under high-end climate change scenarios (up to 99% range loss). Land-use impacts are highly variable across species and scenarios, ranging from severe losses (up to 75% loss) to considerable gains (up to 68% gain) of suitable habitat extent. Rare species thereby tend to be disproportionally affected by both climate and land-use change. COMB projections reveal that land use may amplify, attenuate, or offset changes to suitable habitat extent expected from climate impact depending on species and scenario. Especially in low-end climate change scenarios, land use has the potential to become a game changer in determining the direction and magnitude of range changes, indicating substantial potential for targeted conservation management.

How are European countries planning for sea level rise?

Sea level rise (SLR) is projected to have severe consequences for people and assets in European coastal areas. Planning for SLR is a critical step to ensure timely and adequate responses. Despite our rapidly increasing understanding of SLR impacts and the need to adapt, few studies have looked at how countries are planning for SLR. We surveyed experts from the 32 European countries with a coastline about how their country is planning for SLR. Our online survey focused on four areas: (1) whether SLR planning exists and at what level of government; (2) which climate information and scenarios are used in planning; (3) what planning horizons and corresponding levels of SLR are used; and (4) how uncertainty in handled and whether high-end sea level rise is being considered in planning. Additionally, we asked experts to assess the status of sea level rise planning in their country. Our results indicate that most coastal countries in Europe are planning for SLR, but 25% still do not. We find that the planning horizon 2100 is most common and many countries are considering around 1m (adjusted for local conditions) of SLR at that point in time. However, there are significant differences between countries, which may lead to unequal impacts, over time. We also find that RCP4.5 and RCP8.5 are the most widely used climate change scenarios, suggesting that countries are considering high-end climate change in planning, although this does not mean they consider high amounts of SLR. Important questions remain about how planning is realized into levels of protection or preparedness and whether the amounts of SLR and planning horizons currently in use will lead countries to act in time.

Surveying perceptions and practices of high-end climate change

We surveyed members of the adaptation community about their views on high-end climate change—here defined as global average temperature increase exceeding 2 °C at the end of the century—at consecutive conferences in 2016 and 2018. Most strikingly our surveys show that a majority of the community disagrees that the Paris Agreement has reduced the possibility of the world reaching dangerous levels of climate change. Consistent with this, around two thirds of people consulted are considering high-end climate change or using high-end scenarios in their work all the time, or starting to. However, this is still not done by all. Preparedness for the specific threats posed by high-end impacts is not keeping pace, and more work needs to be done to strengthen the research basis and understand adaptation needs under high-end climate change. Moreover, views on finding information on impacts and tools for decision-making have not changed between 2016 and 2018, showing that there is no improvement. This situation underlines that the adaptation community needs to do better in supporting exchange of information and data between all actors—in addition to finding and filling knowledge gaps. Despite this, there is widespread support for avoiding delaying large-scale adaptation until we have more certainty.

Future heating and cooling degree days for Belgium under a high-end climate change scenario

The local outdoor climate and building characteristics influence the energy use of a building to an important extent. To design energy efficient and climate robust buildings, it is important to get insights into the energy demand over the building's service life from the early design phase onwards. This paper presents an overview of the different variants of the heating and cooling degree day method. A convection-permitting climate model is furthermore used to obtain heating and cooling degree days (for a baseline temperature of 18 °C) for the RCP 8.5 (high-end) climate change scenario for Belgium on a high-resolution grid of 2.8 km. Area of focus for this paper is Belgium. The results demonstrate a decrease of the HDD with 27% between 1976–2004 (3189 HDD) and 2070–2098 (2337 HDD). In contrast, the CDD were found to increase with a factor 2.4 from 167 CDD to 401 CDD in the same timeline. Smaller reductions in average HDD were moreover found in urban areas compared to rural areas. For the CDD, a higher absolute increase was found for urban areas and the Northeast of Belgium.

Impacts of Climate Change and Remote Natural Catastrophes on EU Flood Insurance Markets: An Analysis of Soft and Hard Reinsurance Markets for Flood Coverage

The increasing frequency and severity of natural catastrophes due to climate change is expected to cause higher natural disaster losses in the future. Reinsurance companies bear a large share of this risk in the form of excess-of-loss coverage, where they underwrite the most extreme portion of insurers’ risk portfolios. Past experience has shown that after a very large natural disaster, or multiple disasters in close succession, the recapitalization need of reinsurers could trigger a “hard” reinsurance capital market, where a high demand for capital increases the price charged by investors, which is opposed to a “soft” market, where there is a high availability of capital for reinsurers. Consequently, the rising costs of underwriting are transferred to insurers, which ultimately could trigger higher premiums for natural catastrophe (NatCat) insurance worldwide. Here, we study the vulnerability of riverine flood insurance systems in the EU to global reinsurance market conditions and climate change. To do so, we apply the “Dynamic Integrated Flood Insurance” (DIFI) model, and compare insurance premiums, unaffordability, and the uptake for soft and hard reinsurance market conditions under an average and extreme scenario of climate change. We find that a rising average and higher variance of flood risk towards the end of the century can increase flood insurance premiums and cause higher premium volatility resulting from global reinsurance market conditions. Under a “mild” scenario of climate change, the projected yearly premiums for EU countries, combined, are €1380 higher under a hard compared to a soft reinsurance capital market in 2080. For a high-end climate change scenario, this difference becomes €3220. The rise in premiums causes problems with the unaffordability of flood coverage and results in a declining demand for flood insurance, which increases the financial vulnerability of households to flooding. A proposed solution is to introduce government reinsurance for flood risk, as governments can often provide cheaper reinsurance coverage and are less subject to the volatility of the capital markets.

Modelling the effects of climate change on urban coastal-fluvial flooding

AbstractIn coastal floodplains, high river flows and high coastal water levels can result in extensive flooding. Twenty-first century climate change is expected to alter these flood mechanisms. In this study, a coastal city of Cork, Ireland is used as a case study to investigate changes in flood mechanisms, dynamics and extents due to climate change. A hydrodynamic flood model MSN_Flood was used to compute potential future inundation patterns for a range of climate scenarios based on estimates of current, medium-range and high-end projections of extreme river flows and sea levels. Results illustrate that the flood mechanism is critical in controlling patterns and extent of inundation. Peak river discharges are the primary contributor to extreme flood events under the current climate scenario, however, high-end climate change could result in coastal inundation of comparable magnitude. The most extreme flood events affect the entire city centre – occurring as a result of a combination of fluvial and coastal drivers. The interaction of extreme fluvial discharges and coastal water levels is complex and characterised through comparison of multiple scenarios. This research establishes a best practice methodology for assessment of urban coastal-fluvial flood risk under a changing climate and can be used to determine climate-resilient flood management measures.

Lyme Disease Risks in Europe under Multiple Uncertain Drivers of Change.

Background:Debates over whether climate change could lead to the amplification of Lyme disease (LD) risk in the future have received much attention. Although recent large-scale disease mapping studies project an overall increase in Lyme disease risk as the climate warms, such conclusions are based on climate-driven models in which other drivers of change, such as land-use/cover and host population distribution, are less considered.Objectives:The main objectives were to project the likely future ecological risk patterns of LD in Europe under different assumptions about future socioeconomic and climate conditions and to explore similarity and uncertainty in the projected risks.Methods:An integrative, spatially explicit modeling study of the ecological risk patterns of LD in Europe was conducted by applying recent advances in process-based modeling of tick-borne diseases, species distribution mapping, and scenarios of land-use/cover change. We drove the model with stakeholder-driven, integrated scenarios of plausible future socioeconomic and climate change [the Shared Socioeconomic Pathway (SSPs) combined with the Representative Concentration Pathways (RCPs)].Results:The model projections suggest that future temperature increases may not always amplify LD risk: Low emissions scenarios (RCP2.6) combined with a sustainability socioeconomic scenario (SSP1) resulted in reduced LD risk. The greatest increase in risk was projected under intermediate (RCP4.5) rather than high-end (RCP8.5) climate change scenarios. Climate and land-use change were projected to have different roles in shaping the future regional dynamics of risk, with climate warming being likely to cause risk expansion in northern Europe and conversion of forest to agriculture being likely to limit risk in southern Europe.Conclusions:Projected regional differences in LD risk resulted from mixed effects of temperature, land use, and host distributions, suggesting region-specific and cross-sectoral foci for LD risk management policy. The integrated model provides an improved explanatory tool for the system mechanisms of LD pathogen transmission and how pathogen transmission could respond to combined socioeconomic and climate changes. https://doi.org/10.1289/EHP4615

Towards a Moral Compass to Guide Sustainability Transformations in a High-End Climate Change World

High-end climate change (HECC) raises unprecedented challenges for the transformation of society’s governance arrangements. In such potentially dangerous situation, these challenges have profound moral—rather than only scientific, technical, or managerial—implications. Unfortunately, despite the growing recognition of the necessity for morally-grounded, urgent social-ecological reconfigurations in order to sustainably navigate the uncertain landscape derived from HECC, explicit moral guidance to support the transformation of governance arrangements is still lacking. This work, through the metaphor of a moral compass, proposes a normative tool to support an integrated assessment processes in order to confront the moral challenges and dilemmas in governance and thus favour sustainable transformations under conditions of HECC.

Understanding high-end climate change: from impacts to co-creating integrated and transformative solutions

The world is not yet on track to meet the Paris Agreement climate change target of keeping global average temperature rise within 2 °C above pre-industrial levels. Current greenhouse gas emission trends point to much more substantial warming, with possible increases of 4 °C or more in the long-term. This Special Issue describes findings from the IMPRESSIONS project which advanced the understanding of impacts of high-end climate change (defined as global mean temperatures > 2 °C above pre-industrial levels) and potential solutions for reducing these impacts through adaptation, mitigation and transformative actions. With stakeholders, the project developed a set of integrated climate and socio-economic scenarios and applied these to multi-sectoral impact models in five case studies: Hungary, Scotland, Iberia, Europe as a whole and Central Asia. This showed that benefits in some regions and sectors, such as increasing forest productivity in northern Europe, are offset by detrimental effects in others, such as severe water scarcity, heat stress and loss of productivity in southern Europe and parts of central and eastern Europe, and widespread flood damage. Adaptation and mitigation pathways were generated with stakeholders to address these impacts and identify integrated and transformative solutions. These highlighted the importance of shifting to sustainable lifestyles, good governance for sustainability and climate resilience, and new forms of integrated and sustainable resource management. The stakeholder-led approach of IMPRESSIONS ensured that the research was driven by the priorities of decision-makers, enabling significant co-learning and the identification of robust, innovative and effective solutions for addressing high-end climate change.

Transition pathways to sustainability in greater than 2\xa0\xb0C climate futures of Europe

The complex challenges arising from climate change that exceeds the +2 °C target (termed ‘high-end climate change’) in Europe require new integrative responses to support transformations to a more sustainable future. We present a novel methodology that combines transition management and high-end climate and socioeconomic change scenarios to identify pathways and move Europe closer to sustainability. Eighteen pathways have been co-created with stakeholders through a participatory process. The pathways support Europe in moving towards a desirable future vision, through top-down and bottom-up actions that lower greenhouse gas emissions, reduce impacts of and vulnerabilities to climate and socioeconomic changes and enhance well-being. Analysis shows that the pathways that are robust to future scenario uncertainty are those that shift Europe towards sustainable lifestyles, support and strengthen good governance for sustainability and promote adaptive resource management for water, agriculture and energy. The methodology can support the design of the urgent actions needed to meet the requirements of the Paris Agreement and to transform Europe, in preparation for an uncertain future.

Global glacier volume projections under high-end climate change scenarios

Abstract. The Paris agreement aims to hold global warming to well below 2 ∘C and to pursue efforts to limit it to 1.5 ∘C relative to the pre-industrial period. Recent estimates based on population growth and intended carbon emissions from participant countries suggest global warming may exceed this ambitious target. Here we present glacier volume projections for the end of this century, under a range of high-end climate change scenarios, defined as exceeding +2 ∘C global average warming relative to the pre-industrial period. Glacier volume is modelled by developing an elevation-dependent mass balance model for the Joint UK Land Environment Simulator (JULES). To do this, we modify JULES to include glaciated and unglaciated surfaces that can exist at multiple heights within a single grid box. Present-day mass balance is calibrated by tuning albedo, wind speed, precipitation, and temperature lapse rates to obtain the best agreement with observed mass balance profiles. JULES is forced with an ensemble of six Coupled Model Intercomparison Project Phase 5 (CMIP5) models, which were downscaled using the high-resolution HadGEM3-A atmosphere-only global climate model. The CMIP5 models use the RCP8.5 climate change scenario and were selected on the criteria of passing 2 ∘C global average warming during this century. The ensemble mean volume loss at the end of the century plus or minus 1 standard deviation is -64±5 % for all glaciers excluding those on the peripheral of the Antarctic ice sheet. The uncertainty in the multi-model mean is rather small and caused by the sensitivity of HadGEM3-A to the boundary conditions supplied by the CMIP5 models. The regions which lose more than 75 % of their initial volume by the end of the century are Alaska, western Canada and the US, Iceland, Scandinavia, the Russian Arctic, central Europe, Caucasus, high-mountain Asia, low latitudes, southern Andes, and New Zealand. The ensemble mean ice loss expressed in sea level equivalent contribution is 215.2±21.3 mm. The largest contributors to sea level rise are Alaska (44.6±1.1 mm), Arctic Canada north and south (34.9±3.0 mm), the Russian Arctic (33.3±4.8 mm), Greenland (20.1±4.4), high-mountain Asia (combined central Asia, South Asia east and west), (18.0±0.8 mm), southern Andes (14.4±0.1 mm), and Svalbard (17.0±4.6 mm). Including parametric uncertainty in the calibrated mass balance parameters gives an upper bound global volume loss of 281.1 mm of sea level equivalent by the end of the century. Such large ice losses will have inevitable consequences for sea level rise and for water supply in glacier-fed river systems.

Global water availability under high-end climate change: A vulnerability based assessment

Abstract Global sustainability is intertwined with freshwater security. Emerging changes in global freshwater availability have been recently detected as a combined result of human interventions, natural variability and climate change. Expected future socio-economic and climatic changes will further impact freshwater resources. The quantification of the impacts is challenging due to the complexity of interdependencies between physical and socio-economic systems. This study demonstrates a vulnerability based assessment of global freshwater availability through a conceptual framework, considering transient hydro-climatic impacts of crossing specific warming levels (1.5 °C, 2 °C and 4 °C) and related socio-economic developments under high-end climate change (RCP8.5). We use high resolution climate scenarios and a global land surface model to develop indicators of exposure for 25,000 watersheds. We also exploit spatially explicit datasets to describe a range of adaptation options through sensitivity and adaptive capacity indicators according to the Shared Socioeconomic Pathways (SSPs). The combined dynamics of climate and socio-economic changes suggest that although there is important potential for adaptation to reduce freshwater vulnerability, climate change risks cannot be totally and uniformly eliminated. In many regions, socio-economic developments will have greater impact on water availability compared to climate induced changes. The number of people under increased freshwater vulnerability varies substantially depending on the level of global warming and the degree of socio-economic developments, from almost 1 billion people at 4 °C and SSP5 to almost 3 billion people at 4 °C and SSP3. Generally, it is concluded that larger adaptation efforts are required to address the risks associated with higher levels of warming of 4 °C compared to the lower levels of 1.5 °C or 2 °C. The watershed scale and country level aggregated results of this study can provide a valuable resource for decision makers to plan for climate change adaptation and mitigation actions.

Dryland changes under different levels of global warming

Drylands are vital ecosystems which cover almost 47% of the Earth's surface, hosting 39% of the global population. Dryland areas are highly sensitive to climatic changes and substantial impacts are foreseen under a warming climate. Many studies have examined the evolution of drylands in the future highlighting the need for improved capability of climate models to simulate aridity. The present study takes advantage of new higher resolution climate projections by the HadGEM3A Atmosphere Global Climate Model using prescribed time varying SSTs and sea ice, provided by a range of CMIP5 climate models under RCP8.5. The aim of the higher resolution models is to examine the benefit of the improved representation of atmospheric processes in the dryland research and to see where these results lie in the range of results from previous studies using the original CMIP5 ensemble. The transient response of aridity from the recent past until the end of the 21st century was examined as well as the expansion of global drylands under specific levels of global warming (1.5 °C, 2 °C and 4 °C). Dryland changes were further assessed at the watershed level for a number of major global river basins to discuss implications on hydrological changes and land degradation. The areal coverage of drylands could increase by an additional 7% of the global land surface by 2100 under high end climate change. At a 4 °C warmer world above pre-industrial, 11.2% of global land area is projected to shift towards drier types and 4.24% to wetter. At the same level of warming the number of humans projected to live in drylands varies between 3.3 and 5.2 billion, depending on the socioeconomic developments. By keeping global warming levels to 1.5 °C, up to 1.9 billion people could avoid living in drylands compared to a 4 °C warmer world of low environmental concern.

Modelling dynamic effects of multi-scale institutions on land use change

Formal institutions impact on the dynamics of land use change through their objectives, actions and decision-making processes in response to socio-economic or environmental changes such as climate change. The effects and interplay of these actions are not fully understood, and hence, institutional processes are rarely integrated in modelling analyses of land use change. The complex effects of institutional interactions within land systems can be better understood through modelling approaches that address the heterogeneity of the institutional actors involved and how their decisions affect temporal and spatial dynamics. In this paper, we present an agent-based model of autonomous land managers interacting with institutional agents at two spatial scales. We explore different parameters of institutional intervention (subsidy rate, triggers for action, delay in monitoring, scale-based precedence) under socio-economic drivers and analyse key metrics such as the maximum over- and undersupply of ecosystem services, connectivity of land uses, and degree of change in land use patterns. Levels of subsidy and action triggers have the greatest impact on the magnitude of land use change and the maximum oversupply of ecosystem services. In terms of achieving institutional objectives, subsidy rate is the most important single parameter in the model. Furthermore, we find non-linearity with variations in parameters that have important implications for current land use change modelling and requirements for empirical studies of land use planning institutions. Finally, the effects of high-end climate change may require entirely novel institutional behaviours.

Simulating Hydrological Impacts under Climate Change: Implications from Methodological Differences of a Pan European Assessment

The simulation of hydrological impacts in a changing climate remains one of the main challenges of the earth system sciences. Impact assessments can be, in many cases, laborious processes leading to inevitable methodological compromises that drastically affect the robustness of the conclusions. In this study we examine the implications of different CMIP5-based regional and global climate model ensembles for projections of the hydrological impacts of climate change. We compare results from three different assessments of hydrological impacts under high-end climate change (RCP8.5) across Europe, and we focus on how methodological differences affect the projections. We assess, as systematically as possible, the differences in runoff projections as simulated by a land surface model driven by three different sets of climate projections over the European continent at global warming of 1.5 °C, 2 °C and 4 °C relative to pre-industrial levels, according to the RCP8.5 concentration scenario. We find that these methodological differences lead to considerably different outputs for a number of indicators used to express different aspects of runoff. We further use a number of new global climate model experiments, with an emphasis on high resolution, to test the assumption that many of the uncertainties in regional climate and hydrological changes are driven predominantly by the prescribed sea surface temperatures (SSTs) and sea-ice concentrations (SICs) and we find that results are more sensitive to the choice of the atmosphere model compared to the driving SSTs. Finally, we combine all sources of information to identify robust patterns of hydrological changes across the European continent.

Are European decision-makers preparing for high-end climate change?

Despite the Paris Agreement target of holding global temperature increases 1.5 to 2 °C above pre-industrial levels, high-end climate change (HECC) scenarios going beyond 4 °C are becoming increasingly plausible. HECC may imply increasing climate variability and extremes as well as the triggering of tipping points, posing further difficulties for adaptation. This paper compares the outcomes of four concurrent European case studies (EU, Hungary, Portugal, and Scotland) that explore the individual and institutional conditions, and the information used to underpin adaptation-related decision-making in the context of HECC. The focus is on (i) whether HECC scenarios are used in current adaptation-related decision-making processes; (ii) the role of uncertainty and how climate and non-climate information is used (or not) in these processes; and (iii) the information types (including socio-economic drivers) commonly used and their limitations in relation to HECC scenarios. Decision-makers perceive HECC as having a low probability or distant occurrence and do not routinely account for HECC scenarios within existing climate actions. Decision-makers also perceive non-climate drivers as at least as important, in many cases more important, than climate change alone. Whilst more information about the implications of particular sectoral and cross-sectoral impacts is needed, climate change uncertainty is not a significant barrier to decision-making. Further understanding of individual and institutional challenges brought about by the ‘squeeze’ between adapting to HECC scenarios or to lower levels of temperature change (as those agreed in Paris) is essential to better contextualise the use of climate change information.